In our imagination, human knowledge and technology resemble a vast, Earth-centered space (see Fig. 50.1), which has been continually expanding since early humans first discovered fire and crafted stone tools. This expansion is driven by human innovation. From stone tools to bows and arrows, wheels, and pottery, every historically significant innovation has profoundly transformed human life, making it better—and it is through these transformations that humanity came to recognize the immense value of innovation.